1. Field of the Invention
The present invention is related to a semiconductor integrated circuit device and also to a semiconductor integrated circuit device in which a test by parameters can be performed efficiently.
2. Description of the Related Art
In recent years, a broad range of tests for semiconductor integrated circuit devices before product shipment have been developed together with progress in large scale capacity and high speed while test times are becoming longer.
There are also a broad ranged of testing methods, however, the manufactured semiconductor integrated circuit device is set with a test device (below referred to as a tester), test parameter data are input from the tester and a problem occurs when specific parameters are set in a test which examines data output from the semiconductor integrated circuit device. That is, while the test parameter data are the data formed from a plurality of bits, a problem occurs in the case where, for a certain address, the test parameter data are formed from a bit of a parameter which must be set to an optimal value (below this process is referred to as trimming), and a bit of a parameter with a fixed value. When the bit of a parameter with a fixed value is changed in this type of test parameter data, the bit of a parameter which has already been trimmed for this address is deleted together with the change. As a result, even in the case where a test is performed when only the bit of a parameter with a fixed value of the test parameter data is changed for the same address in which a trimming process has already been performed, it is necessary to repeat the trimming process which increases the time required for testing significantly. Japanese Laid Open Patent 2003-0344500 is used as a reference.
In a test performed using parameters at the time of product shipment, in the case of testing for each address using parameters formed by combining a bit of a parameter which must be trimmed and a bit of a parameter with a fixed value where only the bit of the parameter with a fixed value is changed, the present invention proposes a semiconductor integrated circuit device in which deletion of the bit with the parameter which has been optimally trimmed together with the change of the bit with the parameter with a fixed value for the same address can be prevented, and controlled so that only the bit of a parameter with a fixed value is changed.